This invention relates to a fluid pressure regulator for establishing a selected stable output pressure and particularly to pneumatic regulating valves establishing a constant output pressure with significant changes in the output flow.
Although the invention can be applied to any fluid supply, the primary application has been in connection with pneumatic supply systems. The present invention is therefore discussed in terms of pneumatic systems, although any other gas or other fluid supply can employ the teaching set forth herein.
Generally, a pressure regulator includes a regulating valve including a poppet member which should be pneumatically balanced and unaffected by changes in pneumatic pressure surrounding the valving device in order to produce a precise regulated pressure regulator. Generally, the valving device includes a poppet member moving relative to a valve seat. Various means have been provided for pneumatically balancing the poppet such that it is relatively unaffected by the pneumatic pressure conditions surrounding the poppet. In practical systems, precision pneumatic regulators include a venting valve to relief a small bleed of the supply air from the output chamber to atmosphere or the like. A leakage or bleed orifice between the input and output chambers controls internal balance in a regulator and particularly for minimizing unbalance creating conditions, such as hysteresis in the main valve as a result of trending pressure conditions as well as hysteresis effects in the various relief or bleeding valve systems. Various stablizing systems have been suggested in the prior art. Practical stabilizing systems are shown in U.S. Pat. No. 4,315,520 which issued Feb. 16, 1982 and U.S. Pat. No. 5,358,004 which issued Oct. 25, 1994. The '520 patent discloses a leakage orifice regulator having a special orifice construction to produce a stabilized system as the closure member moves to a close spaced relation and to a closed position. The '004 patent produces a stabilized system wherein a unique leakage port is incorporated into the regulator to continuously by-pass or bleed flow about the main leakport unit of the pressure regulator. Further, the prior art regulators also generally include a substantial number of components, at least some of which require precision construction. The latter construction may result in significant initial cost as well as subsequent maintenance cost. Multi-staged pressure regulators are also often used to provide even more precise pressure control in applications which require or encounter changes in the flow. In multi-staged regulators of known construction, each regulation stage involves a bleed passage for bleeding of the supply air to atmosphere. For example, a multi-stage regulator included a pilot section having a pilot chamber with an orifice unit coupled to the input side of the regulator and to the output side. A relief section had diaphragm members on the opposite sides and connected to oppositely position a relief valve which is connected to position the main or primary regulating valve and which is coupled to the output chamber to bleed fluid to atmosphere through a vent opening. A relatively substantial volume of the supply gas is consumed in the auxiliary bleeds to atmosphere; resulting in an excessive consumption of air. This large consumption is undesirable and in many applications unacceptable.
Fluid pressure regulators generally maintain a constant pressure supply at a given flow of the gas fluid. In many applications, however, a variable flow rate of the fluid may be required or encountered. Pressure regulators for a variable flow application require special construction and generally a multi-stage regulator. Although the prior art has produced pressure regulators for variable flow applications, the prior art regulators are generally of a substantial size and also relatively costly because of the particular constructions. Typically, rather expensive precision fabrication of various components may be required to produce a constant pressure with a change in the flow rate. The large size of prior art regulators may also be undesirable in some installations. A reliable and cost effective pressure regulator producing a constant pressure over a significant flow range is in demand, and particularly as a relatively small, compact structure.
There is therefore a need in the art of pressure regulators for improvements in the various stabilization systems not only to minimize the bleed fluid consumption in multi-stage regulators but to further improve the component costs of the valve construction while improving the stability and functioning of the various elements of pressure regulators, and particularly for applications which a constant pressure is demanded with a flow rate which varies significantly.